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521 headlight help..my fault..duh o!


jammin

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Okay...here it goes.  My lights and everything we in working condition.  As i have moved into the interior of the truck, i decided to take care of the mess of wires where the stereo used to be.  I noticed some spliced wires going into the headlight switch on the dash that were bare...in my (bad decision) hopes of getting them covered, i hit the metal dash with an open wire and "pop"..fuse in the engine bay goes.....so..replace fuse.  Next day, fire up truck...no lights..low or high beam.   Fuses in bay all good.   Did it toast the light switch?   It was not pulled out, and can see no damage to connector....if fuse blew, then don't think it could have killed lights or switch in engine bay?

 

all other lights work...parking, turn, reverse, side marker..but not headlights low or high...thoughts... help or prayers appreciated at this point.  Have wiring diagrams of all systems on truck, so don't think I am missing anything....

 

worst case scenario and it is the switch.,,any aftermarket or datsun interchange switches with other models?  I am so bummed i did this....

 

thanks!

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The second fuse from the inside is the headlight fuse.  It had a thick red wire going into the cab.  By the glove box, is a bunch if connectors.   One of these connectors had the thick red wire passing though it.  The red wire goes to the light switch.  There is also a second wire, on another fuse, going to the light switch.

Headlight on power is on a red wire with a yellow stripe, and this wire goes back through the connectors by the glove box.  This wire goes to the headlight relay, on the inner fender, by the battery.

The headlight relay has four terminals.  Power is applied to the coil, and the switch in the relay.  The relay normally connects the red with yellow wire to the red with black wire, and then the two low beam headlights.

When you push the bright/dim switch on the turn signal, away from you, it grounds the headlight relay coil.  The relay then switches the red with yellow wire to the red with white wire, and the four high beam lights come on. 

The headlights are grounded by a black wire, that goes back to one of the bolts that hold the voltage regulator to the inner fender.

Edited wiring diagram.

HeadlightWires.jpg

full wiring diagram.

521wires.jpg

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Wanted to say thank you for all who replied and also that great wiring diagram....the lights work!  Honestly I don't know how / why.  there was no juice to the switch by the battery in the engine bay, but since i was there i cleaned all the connectors and regreased.  i went back to the dash and forgot i had unplugged the connector to the light switch in the dash when this all started.  put back together..put battery terminal on and tried the lights for grins and they turned on!?  Does the switch in the engine bay reset if no power is to it?  Anyways...life is good. Thanks to all. I am sure i will be asking more questions in the future...next stop, rewiring the reverse lights from the tranny...whoever did the engine swap never wired it back up.

 

Oh yeah...just a tip of my own to help if you are doing electrical repairs...a universal gun cleaning kit with all the wire brushes works awesome for all the electrical sockets and connectors on the truck...I used a .410 size wire brush last night for all the sidemarker lamp sockets..fits perfectly, and a  12 gauge works for turn / brake sockets.  Lastly, a bb gun brush gets into the little baby connectors really nice.....

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The connections in the plugs can go bad after sitting for a while, especially if they get wet, from condensation.   If your front windshield has ever fogged up, there is condensation that has happened on the electrical connectors.  Just unplugging, and plugging the connector back in cuts through the oxidation or corrosion in the connector.

 

The reverse light switch is the lowest, most forward switch on the transmission tail shaft housing, I think.  The reverse light switch gets power on a red with a black stripe wire.  This power is applied anytime the ignition is on.  The wire going back to the reverse lights is also red with a black stripe.

 

It is not uncommon for the ground on the taillights to go bad.  The taillight harness is connected to the taillight frame, that is bolted to the bed, that is bolted to the frame, that is bolted to the engine.  That is a lot of ground connections to go bad.   These connections can also go bad, if exposed to moisture, and most of these grounds are under the truck, where wet road spray gets thrown at them.

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